Autologous T cell responses to primary human colorectal cancer spheroids are enhanced by ectonucleotidase inhibition

OBJECTIVE

T cells are major effectors of the antitumoural immune response. Their activation by tumour-associated antigens can unleash their proliferation and cytotoxic functions, leading to tumour cell elimination. However, tumour-related immunosuppressive mechanisms including the overexpression of immune checkpoints like programmed cell death protein-1 (PD-1), are also engaged, promoting immune escape. Current immunotherapies targeting these pathways have demonstrated weak efficacy in colorectal cancer (CRC). It is thus crucial to find new targets for immunotherapy in this cancer type.

DESIGN

In a prospective cohort of patients with CRC, we investigated the phenotype of tumour-related and non-tumour related intestinal T cells (n=44), particularly the adenosinergic pathway, correlating with clinical phenotype. An autologous coculture model was developed between patient-derived primary tumour spheroids and their autologous tumour-associated lymphocytes. We used this relevant model to assess the effects of CD39 blockade on the antitumour T cell response.

RESULTS

We show the increased expression of CD39, and its co-expression with PD-1, on tumour infiltrating T cells compared with mucosal lymphocytes. CD39 expression was higher in the right colon and early-stage tumours, thus defining a subset of patients potentially responsive to CD39 blockade. Finally, we demonstrate in autologous conditions that CD39 blockade triggers T cell infiltration and tumour spheroid destruction in cocultures.

CONCLUSION

In CRC, CD39 is strongly expressed on tumour infiltrating lymphocytes and its inhibition represents a promising therapeutic strategy for treating patients.

Antitumor immunity induced by antibody-based natural killer cell engager therapeutics armed with not-alpha IL-2 variant

Harnessing innate immunity is emerging as a promising therapeutic approach in cancer. We report here the design of tetraspecific molecules engaging natural killer (NK) cell-activating receptors NKp46 and CD16a, the β-chain of the interleukin-2 receptor (IL-2R), and a tumor-associated antigen (TAA). In vitro, these tetraspecific antibody-based natural killer cell engager therapeutics (ANKETs) induce a preferential activation and proliferation of NK cells, and the binding to the targeted TAA triggers NK cell cytotoxicity and cytokine and chemokine production. In vivo, tetraspecific ANKETs induce NK cell proliferation and their accumulation at the tumor bed, as well as the control of local and disseminated tumors. Treatment of non-human primates with CD20-directed tetraspecific ANKET leads to CD20⁺ circulating B cell depletion, with minimal systemic cytokine release and no sign of toxicity. Tetraspecific ANKETs, thus, constitute a technological platform for harnessing NK cells as next-generation cancer immunotherapies.

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Tetraspecific ANKETs constitute a technological platform to harness NK cells in cancer

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Tetraspecific ANKETs target NKp46, CD16a, IL-2Rβ, and a tumor antigen

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Tetraspecific ANKETs stimulate NK cell proliferation, activation, and antitumor functions

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In vivo, tetraspecific ANKETs promote NK cell tumor accumulation and antitumor activity

851 Harnessing innate immunity in cancer therapies: the example of natural killer cell engagers

Background

Most immunomodulatory approaches have focused on enhancing T-cell responses, with immune checkpoint inhibitors, chimeric antigen receptor T cells or bispecific antibodies. Although these therapies have led to exceptional successes, only a minority of cancer patients benefit from these treatments, highlighting the need to identify new cells and molecules that could be exploited in the next generation of immunotherapy. Given the crucial role of innate immune responses in immunity, harnessing these responses opens up new possibilities for tumor control. Antibody engineering provides us with great opportunities to induce synthetic immunity and to optimize the biological functions of innate immune cells, in particular by boosting the capacity of Natural Killer (NK) cells to kill tumor cells directly and to stimulate T-cell responses indirectly.

Methods

In order to leverage the advantages of harnessing NK cell effector functions, we used our Antibody-based NK cell Engager Therapeutics (ANKET) molecular platform1 and designed a new generation of molecules that can engage activating receptors NKp46 and CD16, the IL-2Rβ chain and a tumor antigen in a single tetra-specific molecule (ANKET4). The variant of interleukin-2 (IL-2v) integrated in the ANKET4 molecule is unable to bind the α-subunit of its receptor to limit regulatory T cell activation and IL-2Rα-mediated toxicity.

Results

In vitro, ANKET4 provides proliferation and activation signals targeted to NK cells and induces primary human NK cell cytolytic activity and the secretion of cytokines and chemokines only after binding to the tumor target. In mouse models of both invasive and solid tumors, ANKET4 induced NK cell proliferation and accumulation at the tumor bed, and had a higher anti-tumor efficacy than approved therapeutic antibodies targeting the same tumor antigen. Mechanistically, transcriptomic analysis and in-vivo studies revealed that the geometry of the ANKET4 molecule including NKp46, CD16 and IL-2 receptor binding moieties on the same molecule was essential for its strong activity which results from a synthetic cooperativity between immunoreceptor tyrosine-based activation motif (ITAM) and cytokine signaling pathways. In non-human primates, CD20-directed ANKET4 resulted in sustained CD20+ B-cell depletion with minimal systemic cytokine release and no clinical sign of toxicity.

Conclusions

Tetra-specific ANKET4 thus constitutes a technological platform combining the induction of NK cell proliferation and effector functions with a manageable safety profile, supporting its clinical development for next-generation cancer immunotherapies.

Reference

Gauthier L, Morel A, Anceriz N, Rossi B, Blanchard-Alvarez A, Grondin G, et al. Multifunctional natural killer cell engagers targeting NKp46 trigger protective tumor immunity. Cell 2019;177(7):1701–13 e16.

Ethics Approval

Primary immune cells were purified from buffy coats from healthy donors obtained from Etablissement Francais du Sang (EFS, Marseille) with written consent from each volunteer.All mouse experiments were performed in accordance with the rules of the Innate Pharma ethics committee and were approved by the Ministère de l’Enseignement Supérieur, de la Recherche et de l’Innovation – France (APAFIS# 19272 ).All non human-primate procedures were conducted according to European guidelines for animal care and use for scientific purposes (Directive 63-2010, ”Journal Officiel des Communautés Européennes”, L276, September 22, 2010) and according to CEA institutional guidelines. The study was approved by the local ethical committee under the number A18_080 and by the French Administration (APAFIS#20525-2019050616506478 v1)

Targeting MICA/B with cytotoxic therapeutic antibodies leads to tumor control

Background: MICA and MICB are tightly regulated stress-induced proteins that trigger the immune system by binding to the activating receptor NKG2D on cytotoxic lymphocytes. MICA and MICB are highly polymorphic molecules with prevalent expression on several types of solid tumors and limited expression in normal/healthy tissues, making them attractive targets for therapeutic intervention. Methods: We have generated a series of anti-MICA and MICB cross-reactive antibodies with the unique feature of binding to the most prevalent isoforms of both these molecules. Results: The anti-MICA and MICB antibody MICAB1, a human IgG1 Fc-engineered monoclonal antibody (mAb), displayed potent antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) of MICA/B-expressing tumor cells in vitro. However, it showed insufficient efficiency against solid tumors in vivo, which prompted the development of antibody-drug conjugates (ADC). Indeed, optimal tumor control was achieved with MICAB1-ADC format in several solid tumor models, including patient-derived xenografts (PDX) and carcinogen-induced tumors in immunocompetent MICAgen transgenic mice. Conclusions: These data indicate that MICA and MICB are promising targets for cytotoxic immunotherapy.

Targeting MICA/B with cytotoxic therapeutic antibodies leads to tumor control

Background: MICA and MICB are tightly regulated stress-induced proteins that trigger the immune system by binding to the activating receptor NKG2D on cytotoxic lymphocytes. MICA and MICB are highly polymorphic molecules with prevalent expression on several types of solid tumors and limited expression in normal/healthy tissues, making them attractive targets for therapeutic intervention. Methods: We have generated a series of anti-MICA and MICB cross-reactive antibodies with the unique feature of binding to the most prevalent isoforms of both these molecules. Results: The anti-MICA and MICB antibody MICAB1, a human IgG1 Fc-engineered monoclonal antibody (mAb), displayed potent antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) of MICA/B-expressing tumor cells in vitro. However, it showed insufficient efficiency against solid tumors in vivo, which prompted the development of antibody-drug conjugates (ADC). Indeed, optimal tumor control was achieved with MICAB1-ADC format in several solid tumor models, including patient-derived xenografts (PDX) and carcinogen-induced tumors in immunocompetent MICAgen transgenic mice. Conclusions: These data indicate that MICA and MICB are promising targets for cytotoxic immunotherapy.

NKp46 is a diagnostic biomarker and may be a therapeutic target in gastrointestinal T-cell lymphoproliferative diseases: a CELAC study

OBJECTIVES

Primary GI T-cell lymphoproliferative diseases (T-LPD) are heterogeneous entities, which raise difficult diagnosis and therapeutic challenges. We have recently provided evidences that lymphomas complicating coeliac disease (CD) arise from innate-like lymphocytes, which may carry NK receptors (NKRs).

DESIGN

NKRs expression was compared by flow cytometry in intraepithelial lymphocytes (IEL) from CD, type I or type II refractory CD (RCD). NKp46 was next assessed by immunohistochemistry in paraffin-embedded biopsies from 204 patients with CD, RCDI, RCDII or GI T-cell lymphomas and from a validation cohort of 61 patients. The cytotoxic properties of an anti-NKp46 monoclonal antibody conjugated to pyrrolobenzodiazepine (PBD) was tested ex vivo in human primary tumour cells isolated from fresh duodenal biopsies.

RESULTS

NKp46 (but not CD94, NKG2A, NKG2C, NKG2D) was significantly more expressed by malignant RCDII IEL than by normal IEL in CD and RCDI. In paraffin biopsies, detection of >25 NKp46+ IEL per 100 epithelial cells discriminated RCDII from CD and RCDI. NKp46 was also detected in enteropathy-associated T-cell lymphomas (EATL, 24/29) and in monomorphic epitheliotropic intestinal T-cell lymphomas (MEITL, 4/4) but not in indolent T-LPD (0/15). Treatment with anti-NKp46-PBD could efficiently and selectively kill human NKp46+ primary IEL ex vivo.

CONCLUSION

NKp46 is a novel biomarker useful for diagnosis and therapeutic stratification of GI T-LPD. Strong preclinical rationale identifies anti-NKp46-PBD as a promising therapy for RCDII, EATL and MEITL.

Anti-NKG2A mAb Is a Checkpoint Inhibitor that Promotes Anti-tumor Immunity by Unleashing Both T and NK Cells

Checkpoint inhibitors have revolutionized cancer treatment. However, only a minority of patients respond to these immunotherapies. Here, we report that blocking the inhibitory NKG2A receptor enhances tumor immunity by promoting both natural killer (NK) and CD8⁺ T cell effector functions in mice and humans. Monalizumab, a humanized anti-NKG2A antibody, enhanced NK cell activity against various tumor cells and rescued CD8⁺ T cell function in combination with PD-x axis blockade. Monalizumab also stimulated NK cell activity against antibody-coated target cells. Interim results of a phase II trial of monalizumab plus cetuximab in previously treated squamous cell carcinoma of the head and neck showed a 31% objective response rate. Most common adverse events were fatigue (17%), pyrexia (13%), and headache (10%). NKG2A targeting with monalizumab is thus a novel checkpoint inhibitory mechanism promoting anti-tumor immunity by enhancing the activity of both T and NK cells, which may complement first-generation immunotherapies against cancer.

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Blocking NKG2A unleashes both T and NK cell effector functions

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Combined blocking of the NKG2A and the PD-1 axis promotes anti-tumor immunity

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Blocking NKG2A and triggering CD16 illustrates the efficacy of dual checkpoint therapy

Abstract 2714: Combination of monalizumab and durvalumab as a potent immunotherapy treatment for solid human cancers

Inhibitory CD94-NKG2A (Natural Killer Group 2A) receptors are expressed on subsets of natural killer (NK) cells, γδ and CD8+ T cells. HLA-E (Human Leukocytes Antigen-E), the ligand for CD94-NKG2A, is upregulated on cancer cells of several solid tumors, providing a negative regulatory signal to tumor-infiltrating lymphocytes (TILs). Blockade of this immune checkpoint pathway with anti-NKG2A monoclonal antibodies (Ab) enhances NK cell responses to tumor cells in vitro and in humanized mice. Here, we describe NK and CD8+ T cell infiltrates in several human solid tumors by immunohistochemistry (IHC) and multicolor flow cytometry. We then studied the effects of in vitro targeting both pathways on primary human NK and CD8+ T cells. By using IHC on formalin-fixed paraffin-embedded samples on cohorts of solid tumors i.e. non-small cell lung cancer (NSCLC, n=45), stomach tumor (n=76), colorectal cancer (CRC, n=103), head and neck tumor (HNSCC, n=68), pancreatic tumors (n=77) and renal cell carcinoma (RCC, n=75), we observed NKp46+ NK cells in the large majority of cancer types (especially in RCC, HNSCC and stomach cancers). CD8+ T cells were found at significantly higher densities in all tumor types. In another cohort of HNSCC samples (n=60), higher proportions of CD94+ lymphocytes were found within the tumor islets both in the primary tumors and in the metastatic lymph nodes. In addition, in CRC patients with liver metastasis (n=101), high CD94+ cell densities were associated with poor overall survival. These data suggest that NKG2A blockade might unleash NK and T cells that are present in close contact to tumor cells. As previously shown, we confirmed that CD94-NKG2A ligand, HLA-E, was expressed by tumor cells in the large majority of solid tumor. In addition, high PD-L1 expressions were observed in NSCLC, stomach tumors, CRC and HNSCC. Flow cytometry analyses revealed that NK and CD8+ T cells co-expressing NKG2A and PD-1 were more numerous in tumor compared to matched peripheral blood and adjacent tissues of NSCLC and HNSCC patients. To mimic the “NKG2A+PD-1+” TILs phenotype, chronic stimulation of peripheral blood cells from healthy volunteers was performed using IL-15. The conditions led to the induction of NKG2A and PD-1 on NK and antigen-specific CD8+ T cell subsets. These effector cells were then co-cultured with tumor cell lines expressing HLA-E +/- PD-L1. We showed that monalizumab, a first-in class anti-NKG2A Ab, combined with durvalumab resulted in higher responses (CD107 mobilization and IFN-γ production) compared to each Ab alone. These data were confirmed in a syngeneic mouse model where both NK and CD8+ T cells were found to be involved in tumor rejection. Together, these data confirm that blocking NKG2A can potentiate the anti-tumor efficacy of PD-1 inhibitors and support the rationale for ongoing clinical trials investigating the monalizumab/durvalumab combination (NCT02671435 and NCT03088059).

Citation Format: Caroline Soulas, Romain Remark, Vedran Brezar, Julie Lopez, Elodie Bonnet, Flavien Caraguel, Ana Lalanne, Caroline Hoffmann, Caroline Denis, Thomas Arnoux, Clarisse Caillet, Arnaud Dujardin, Guillaume Habif, Olivier Lantz, Cécile Bonnafous, Eric Vivier, Pascale Andre. Combination of monalizumab and durvalumab as a potent immunotherapy treatment for solid human cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2714.

Abstract CT158: Phase II study of monalizumab, a first-in-class NKG2A monoclonal antibody, in combination with cetuximab in previously treated recurrent or metastatic squamous cell carcinoma of the head and neck (R/M SCCHN): Preliminary assessment of safety and efficacy

Background Monalizumab is an immune checkpoint inhibitor targeting NKG2A receptors expressed on subsets of tumor-infiltrating cytotoxic CD8 T cells and Natural Killer (NK) cells. NKG2A ligand is HLA-E, a non-classical HLA class I molecule often upregulated in cancer. Preclinical experiments have shown that blocking NKG2A binding to HLA-E may promote NK and T cell anti-tumor responses. NK cell stimulation with a checkpoint inhibitor might also enhance antibody dependent cellular cytotoxicity (ADCC) induced by cetuximab. Although approved in SCCHN after platinum-based therapy, cetuximab has limited activity in that setting (12% response rate).

Methods This is a multicenter non-randomized study (NCT02643550). After previous exploration of 5 dose levels of monalizumab (0.4, 1, 2, 4 or 10 mg/kg every 2 weeks) in combination with fixed doses of cetuximab (400 mg/m² load then 250 weekly) using a 3+3 design, the cohort expansion used monalizumab at the highest dose tested (10 mg/kg) and included a futility analysis after the first 11 patients (pts). The trial was open to pts ≥ 18 years old with SCCHN progressing after platinum-based therapy with no more than 2 previous lines, regardless of HLA-E or human papilloma virus status. The primary endpoint for anti-tumor activity was overall response rate per RECIST, assessed every 8 weeks. Pts were treated until disease progression or unacceptable toxicity.

Results As of 12/19/2017, 26 pts were enrolled in the expansion part, and 16 pts had a minimum of 16 weeks of follow-up to be evaluable for efficacy. The safety profile was as expected, similar to the single agent experience with either agent. The majority of adverse events (AE) were of Grade 1-2 severity, rapidly reversible and easily manageable, with 3 treatment-related grade 3-4 AE and 1 pt stopped monalizumab due to safety. Median age was 62 years (range: 34-77); 56 % were male; PS was 0 or 1; 4 were HPV+. All 16 pts had received prior platinum-based therapy, 8 prior immune therapy, 2 prior cetuximab with radiation. There were 6 pts with partial responses (PR) (4 confirmed; 2 not yet confirmed) of whom 2 were previously treated with immune therapy and 1 had disease deemed resistant to cetuximab. Median treatment duration for confirmed PR is 25+ weeks (16, 23+, 28+, 35+), 9 pts had stable disease (SD). The study was not stopped for futility and is planned to enroll up to 40 pts. Further follow-up is needed to evaluate duration of response, progression-free and overall survival.

Conclusion Preliminary data suggest promising antitumor activity of the combination of monalizumab and cetuximab compared to historical data with single agent cetuximab, with acceptable safety. These encouraging results will need to be confirmed on larger sample size with longer follow up.

Citation Format: Roger Cohen, Jérôme Fayette, Marshall Posner, Gautier Lefebvre, Jessica Bauman, Sébastien Salas, Caroline Even, Tanguy Seiwert, Dimitrios Colevas, Antonio Jimeno, Esma Saada, Barbara Burtness, Pascale André, Carine Paturel, Cécile Bonnafous, Anne-Marie Soulié, Anne Tirouvanziam-Martin, Robert Zerbib, Agnès Boyer-Chammard. Phase II study of monalizumab, a first-in-class NKG2A monoclonal antibody, in combination with cetuximab in previously treated recurrent or metastatic squamous cell carcinoma of the head and neck (R/M SCCHN): Preliminary assessment of safety and efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT158.

Abstract 1690: NKG2A immune checkpoint blockade potentiates cetuximab induced ADCC in head and neck cancer preclinical model

Monalizumab (IPH2201) is a first-in-class humanized IgG4 targeting NKG2A (Natural Killer Group 2A), which is expressed as a heterodimer with CD94 at the surface of subsets of NK (Natural Killer) cells, γδ T cells and tumor infiltrating CD8+ T cells. This inhibitory receptor binds to HLA-E (Human Leukocytes Antigen-E) molecules that are frequently up-regulated on human cancer cells, preventing from killing by NKG2A+ immune cells. HLA-E is expressed on most of the patients with Head and Neck Squamous Cell Cancer (HNSCC). Monalizumab blocks the binding of CD94/NKG2A to HLA-E, reducing inhibitory signaling thereby unleashing NK and T cell responses. High expression of EGFR occurs in most epithelial malignancies and particularly in HNSCC and is associated with poor prognosis. The anti-EGFR monoclonal antibody cetuximab (Ctx) is thought to act through blocking oncogenic signaling and by inducing Fcγ receptor-mediated antibody dependent cell cytotoxicity (ADCC) which involves human NK cells. We investigated ex vivo and in vitro the rationale of combining monalizumab with Ctx in the treatment of oral cancers. We first analyzed formalin-fixed paraffin-embedded samples of HNSCC patients by immunohistochemistry (n=65). We confirmed that HLA-E was expressed on carcinoma cells in all patients. We also observed that most of the tumors were highly infiltrated by CD8+ T cells both in the tumor beds and in the stroma and that the majority of tumors were also infiltrated by NKp46+ NK cells in higher numbers in the non-metastatic tumors. Interestingly, HNSCC was found as being one of the tumor types with the highest NKp46+ cell density as compared with renal cell carcinoma, non-small cell lung cancer, colorectal cancer or pancreatic tumors. Moreover CD94+ lymphocytes were detected in the stroma and tumor beds in close contact to tumor cells in about half of the patients. Using multicolor flow cytometry, NK cells and CD8+ T cells from tumor and non-involved adjacent tissues, metastatic lymph nodes and peripheral blood from patients relapsing post-chemotherapy were characterized for expression of activating and inhibitory receptors. Interestingly, NKG2A expression was higher on tumor infiltrating NK cells (CD56dim or CD56bright) and CD8+ T cell compared to the one observed in non-involved adjacent tissue, metastatic lymph node or blood. In vitro, monalizumab increased CD107 mobilization and CD137 upregulation on NKG2A+ NK cells in response to HNSCC cell lines with endogenous HLA-E expression and enhanced Ctx-mediated ADCC in a dose dependent manner. Altogether, these data support the rationale for investigating monalizumab in HNSCC patients and in combination with cetuximab in clinical trials (NCT02643550).

Citation Format: Caroline Soulas, Ana Lalanne, Cécile Bonnafous, Caroline Hoffman, Elodie Bonnet, Arnaud Dujardin, Violette Breso, Mathieu Bléry, Olivier Lantz, Romain Remark, Eric Vivier, Pascale Andre. NKG2A immune checkpoint blockade potentiates cetuximab induced ADCC in head and neck cancer preclinical model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1690.

Abstract 2342: NKG2A immune checkpoint blockade enhances the anti-tumor efficacy of PD1/PD-L1 inhibitors in a preclinical model

Monalizumab (IPH2201) is a novel, first-in-class humanized IgG4 targeting the immune checkpoint receptor NKG2A (Natural Killer Group 2A). NKG2A is expressed as a heterodimer with CD94 on the surface of subsets of cytotoxic lymphocytes: NK (Natural Killer) cells, γδ T cells and tumor infiltrating CD8 T lymphocytes. CD94/NKG2A is an inhibitory receptor that binds to HLA-E (Human Leukocyte Antigen-E) in humans and orthologous Qa-1b in mice. Upon ligand binding, CD94/NKG2A triggers inhibitory signaling that reduces NK and CD8 T cell responses. HLA-E is frequently up-regulated on cancer cells of many solid tumors or hematological malignancies, protecting from killing by NKG2A+ immune cells. By blocking the binding of CD94/NKG2A to HLA-E, monalizumab leads to enhancement of NK and cytotoxic T cell responses.

The immune checkpoint receptor programmed cell death 1 (PD-1) is another inhibitory receptor widely upregulated by tumor-infiltrating T lymphocytes (TILs). In many tumor types immune surveillance is hampered by the expression of PD-L1, one of the ligands of PD-1. Blocking the PD-1 pathway has proven efficient as anti-tumor therapy. Nevertheless many patients remain refractory to these therapeutics. Combination treatment with PD-1 blockers and mAb to a second checkpoint receptor, CTLA-4, have proven effective only for some patients, suggesting a need for combining with other checkpoint blockers.

The A20 cell line is a mouse B cell lymphoma line that expresses PD-L1, but not Qa-1b. Upon subcutaneous injection into Balb/c mice, A20 formed solid tumors in which PD-L1 expression was retained and where Qa-1b expression was induced. A20 tumor growth was controlled by NK and CD8 T cells. In spite of high expression of PD-1 on many immune infiltrating cells, and high expression of PD-L1 on tumor cells, monotherapy with anti-PD-1 or -PD-L1 mAb resulted in only moderate reduction in tumor growth.

Interestingly, more than 50% of A20 tumor infiltrating NK cells and about 10% of CD8 T cells expressed CD94/NKG2A. The NKG2A+ CD8 T cell population also co-expressed PD-1. Qa-1b expression was induced not only on the surface of tumor cells but also on infiltrating immune cells in vivo. Consistent with the hypothesis that Qa-1b protects tumor cells from killing by NKG2A+ effector NK and T cells, treatment with an antibody that blocks NKG2A significantly delayed A20 tumor growth. Mice were then treated with both anti-NKG2A and anti-PD-1 or -PD-L1 in combination. These combinations resulted in significantly higher anti-tumor responses compared to monotherapies, characterized by an increased frequency of complete tumor cell regression.

Together, these data indicate that blocking NKG2A in conjunction with PD-1/PD-L1 checkpoint inhibitors could provide synergistic anti-tumor efficacy and support the rationale for investigating this combination in clinical trials.

Citation Format: Caroline Sola, Thomas Arnoux, Fabien Chanuc, Nicolas Fuseri, Benjamin Rossi, Laurent Gauthier, Corinne Leget, Cécile Bonnafous, Nicolai Wagtmann, Yannis Morel, Pascale André. NKG2A immune checkpoint blockade enhances the anti-tumor efficacy of PD1/PD-L1 inhibitors in a preclinical model. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2342.

A novel targeted immunotherapy for CTCL is on its way: Anti-KIR3DL2 mAb IPH4102 is potent and safe in non-clinical studies

Cutaneous T-cell lymphomas (CTCLs) represent a group of rarely occurring and clinically and pathologically heterogeneous diseases that are considered incurable at advanced stages. Current treatments provide limited clinical benefit and are thus largely amenable to improvement. An antibody-based CTCL-specific immunotherapy targeting the KIR3DL2 receptor expressed by the tumor cells in CTCL is currently under development and has shown encouraging results in pre-clinical studies.

Site-Specific Conjugation of Monomethyl Auristatin E to Anti-CD30 Antibodies Improves Their Pharmacokinetics and Therapeutic Index in Rodent Models

Antibody-drug conjugates (ADCs) have demonstrated clinical benefits that have led to the recent FDA approval of KADCYLA and ADCETRIS. Most ADCs that are currently in clinical use or development, including ADCETRIS, are produced by chemical conjugation of a toxin via either lysine or cysteine residues, inevitably leading to heterogeneous products with variable drug-to-antibody ratios (DARs). Here, we describe the in vitro and in vivo characterization of four novel ADCs that are based on the anti-CD30 antibody cAC10, which has the same polypeptide backbone as ADCETRIS, and compare the results with the latter. Bacterial transglutaminase (BTG) was exploited to site-specifically conjugate derivatives of monomethyl auristatin E (all comprising a cleavable linker) to the glutamine at positions 295 and 297 of cAC10, thereby yielding homogeneous ADCs with a DAR of 4. In vitro cell toxicity experiments using two different CD30-positive cell lines (Karpas 299 and Raji-CD30(+)) revealed comparable EC50 values for ADCETRIS (1.8 ± 0.4 and 3.6 ± 0.6 ng/mL, respectively) and the four cAC10-based ADCs (2.0 ± 0.4 to 4.9 ± 1.0 ng/mL). Quantitative time-dependent in vivo biodistribution studies (3-96 h p.i.) in normal and xenografted (Karpas 299 cells) SCID mice were performed with a selected (125)I-radioiodinated cAC10 ADC and compared with that of (125)I-ADCETRIS. The chemo-enzymatically conjugated, radioiodinated ADC showed higher tumor uptake (17.84 ± 2.2% ID/g 24 h p.i.) than (125)I-ADCETRIS (10.5 ± 1.8% ID/g 24 h p.i.). Moreover, (125)I-ADCETRIS exhibited higher nontargeted liver and spleen uptake. In line with these results, the maximum tolerated dose of the BTG-coupled ADC (>60 mg/kg) was significantly higher than that of ADCETRIS (18 mg/kg) in rats. These results suggest that homogeneous ADCs display improved pharmacokinetics and better therapeutic indexes compared to those of chemically modified ADCs with variable DARs.

IPH4102, a humanized KIR3DL2 antibody with potent activity against cutaneous T-cell lymphoma

Advanced cutaneous T-cell lymphoma (CTCL) remains an unmet medical need, which lacks effective targeted therapies. In this study, we report the development of IPH4102, a humanized monoclonal antibody that targets the immune receptor KIR3DL2, which is widely expressed on CTCL cells but few normal immune cells. Potent antitumor properties of IPH4102 were documented in allogeneic human CTCL cells and a mouse model of KIR3DL2(+) disease. IPH4102 antitumor activity was mediated by antibody-dependent cell cytotoxicity and phagocytosis. IPH4102 improved survival and reduced tumor growth in mice inoculated with KIR3DL2(+) tumors. Ex vivo efficacy was further evaluated in primary Sézary patient cells, sorted natural killer-based autologous assays, and direct spiking into Sézary patient peripheral blood mononuclear cells. In these settings, IPH4102 selectively and efficiently killed primary Sézary cells, including at unfavorable effector-to-target ratios characteristic of unsorted PBMC. Together, our results offer preclinical proof of concept for the clinical development of IPH4102 to treat patients with advanced CTCL.

Abstract 5037: Targeting MICA with therapeutic antibodies for the treatment of cancer

MICA and MICB, along with ULPBs, are ligands for the activating receptor NKG2D expressed on NK cells and subsets of T cells in Human. NKG2D ligands are induced by cellular stress and pathogen infections. Their expression is tightly regulated by complex mechanisms both at the mRNA and protein levels. In the case of MICA and MICB, more than 65 and 30 alleles respectively were described with different properties regarding to their cellular location adding to the complexity of this recognition system. Nevertheless, as markers of cellular stress, in particular in tumorigenesis, MICA and the closely related MICB proteins are candidates of choice to be targeted by a cytotoxic therapeutic antibody. We first evaluated MICA/B expression by immunohistochemistry on healthy tissues and tumors to validate these antigens as therapeutic targets. Then, using mouse immunization, we generated a panel of chimeric human IgG1 monoclonal antibodies targeting MICA and MICB. These mAbs have the ability to bind to several structurally different alleles and to cross-react on MIC proteins from cynomolgus macaques. Their capacity to block the MICA/NKG2D interaction was assessed by surface plasmon resonance as well as by using cell-based assays. In vitro efficacy was measured by the capacity to mediate complement-dependent cytotoxicity (CDC) and antibody-dependent cell cytotoxicity (ADCC) towards MICA expressing cells. In vivo efficacy of the anti-MICA mAbs was measured in both a preventive and a curative setting using MICA expressing cell lines. Altogether, we have generated a panel of anti-MICA mAbs with diverse functional properties. Ongoing work aims to choose the best candidate for humanization and further clinical development.

Citation Format: Mathieu Blery, Cécile Bonnafous, Valentine Peri, Sylvia Trichard, Ivan Perrot, Stéphanie Cornen, Ariane Thielens, Violette Breso, Yannis Morel, François Romagne, Benjamin Rossi, Carine Paturel, Laurent Gauthier. Targeting MICA with therapeutic antibodies for the treatment of cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5037. doi:10.1158/1538-7445.AM2014-5037

In vivo interferon-alpha/ribavirin treatment modulates Vγ9Vδ2 T-cell function during chronic HCV infection

In chronic hepatitis C virus (HCV) infection, treatment failure and defective host immune response highly demand improved therapy strategies. Vγ9Vδ2 T-cells represent a good target for HCV immunotherapy, since phosphoantigen (PhAg)-activated Vγ9Vδ2 T-lymphocytes are able to inhibit subgenomic HCV replication by interferon (IFN)-γ release. A profound impairment of IFN-γ production by Vγ9Vδ2 T-cells during chronic HCV infection was previously shown. Interestingly, in vitro IFN-α partially restored Vγ9Vδ2 T-cells responsiveness to PhAg, by stabilizing IFN-γ-mRNA. To verify how in vivo IFN-α/ribavirin (RBV) treatment could affect Vγ9Vδ2 T-cells phenotype and responsiveness to PhAg in HCV-infected patients, 10 subjects underwent a longitudinal study before and after treatment. IFN-α/RBV therapy did not significantly modify Vγ9Vδ2 T-cell numbers and differentiation profile. Interestingly, Vγ9Vδ2 T-cell responsiveness remained unmodified until 3 weeks of therapy, but dropped after 1 month, suggesting that repeated in vivo IFN-α administration in the absence of T-cell receptor (TCR)-mediated signals results in Vγ9Vδ2 T-cell anergy. The present work defines the window of possible application of combined strategies targeting Vγ9Vδ2 T-cells during chronic HCV infection; specifically, the first 3 weeks from the beginning of treatment may represent the optimal time to target Vγ9Vδ2 T-cells in vivo, since their function in terms of IFN-γ production is preserved.

Interferon-α improves phosphoantigen-induced Vγ9Vδ2 T-cells interferon-γ production during chronic HCV infection

In chronic HCV infection, treatment failure and defective host immune response highly demand improved therapy strategies. Vγ9Vδ2 T-cells may inhibit HCV replication in vitro through IFN-γ release after Phosphoantigen (PhAg) stimulation. The aim of our work was to analyze Vγ9Vδ2 T-cell functionality during chronic HCV infection, studying the role of IFN-α on their function capability. IFN-γ production by Vγ9Vδ2 T-cells was analyzed in vitro in 24 HCV-infected patients and 35 healthy donors (HD) after PhAg stimulation with or without IFN-α. The effect of in vivo PhAg/IFN-α administration on plasma IFN-γ levels was analyzed in M. fascicularis monkeys. A quantitative analysis of IFN-γ mRNA level and stability in Vγ9Vδ2 T-cells was also evaluated. During chronic HCV infection, Vγ9Vδ2 T-cells showed an effector/activated phenotype and were significantly impaired in IFN-γ production. Interestingly, IFN-α was able to improve their IFN-γ response to PhAg both in vitro in HD and HCV-infected patients, and in vivo in Macaca fascicularis primates. Finally, IFN-α increased IFN-γ-mRNA transcription and stability in PhAg-activated Vγ9Vδ2 T-cells. Altogether our results show a functional impairment of Vγ9Vδ2 T-cells during chronic HCV infection that can be partially restored by using IFN-α. A study aimed to evaluate the antiviral impact of PhAg/IFN-α combination may provide new insight in designing possible combined strategies to improve HCV infection treatment outcome.

Large scale expansion of Vgamma9Vdelta2 T lymphocytes from human peripheral blood mononuclear cells after a positive selection using MACS "TCR gamma/delta+ T cell isolation kit"

Interest in gamma9delta2 T cells has increased greatly in the past decade. While several protocols allowed the amplification of a large proportion of these cells in vitro, the purity of the final preparation is usually heterogeneous between different donors. Functional studies of this population are often controversial due to the presence of other populations such as NK cells which share a wide range of characteristics. Here, the gamma9delta2 T cells labelled-fraction is purified and mixed with the irradiated unlabelled fraction followed by a single stimulation with phosphoantigen, in turn followed by a classical step of amplification in the presence of interleukin 2. In this study, we describe a straightforward protocol to amplify pure populations of gamma9delta2 T cells which could be useful in fundamental research or in the development of a new generation of gammadelta cell therapy protocol.

Improved Brain Uptake and Pharmacological Activity Profile of Morphine-6-Glucuronide Using a Peptide Vector-Mediated Strategy

Morphine-6-glucuronide (M6G), an active metabolite of morphine, has been shown to have significantly attenuated brain penetration relative to that of morphine. Recently, we have demonstrated that conjugation of various drugs to peptide vectors significantly enhances their brain uptake. In this study, we have conjugated morphine-6-glucuronide to a peptide vector SynB3 to enhance its brain uptake and its analgesic potency after systemic administration. We show by in situ brain perfusion that vectorization of M6G (Syn1001) markedly enhances the brain uptake of M6G. This enhancement results in a significant improvement in the pharmacological activity of M6G in several models of nociception. Syn1001 was about 4 times more potent than free M6G (ED(50) of 1.87 versus 8.74 micromol/kg). Syn1001 showed also a prolonged duration of action compared with free M6G (300 and 120 min, respectively). Furthermore, the conjugation of M6G results in a lowered respiratory depression, as measured in a rat model. Taken together, these data strongly support the utility of peptide-mediated strategies for improving the efficacy of drugs such as M6G for the treatment of pain.

Peptide-vector strategy bypasses P-glycoprotein efflux, and enhances brain transport and solubility of paclitaxel

We present the results obtained with paclitaxel coupled to a peptide-vector SynB3 (PAX-OSUC-SynB3), showing that this peptide-vector enhances the solubility of paclitaxel and its brain uptake in mice using the in situ brain perfusion model. We also show by the in situ brain perfusion in P-glycoprotein (P-gp)-deficient and wild-type mice that vectorized paclitaxel bypasses the P-gp present at the luminal side of the blood-brain barrier. The effect of the vectorized paclitaxel on various cancer cells was not significantly different from that of free paclitaxel. These results indicate that vectorization of paclitaxel may have significant potential for the treatment of brain tumors.

Characterization of a novel putative cognition enhancer mediating facilitation of glycine effect on strychnine-resistant sites coupled to NMDA receptor complex

The effects of (S)-4-amino-5-[(4,4-dimethylcyclohexyl)amino]-5-oxo-pentanoic acid ((S)CR 2249), a new chemical entity selected among a series of glutamic acid derivatives, were investigated on N-methyl-D-aspartate (NMDA)-evoked release of [3H]noradrenaline from rat hippocampal slices. (S)CR 2249 facilitated glycine-mediated reversion of kynurenate antagonism at strychnine-insensitive glycine receptors coupled to the NMDA receptor. The potency of glycine (EC50 = 21.5 microM +/- 4.2) was not significantly influenced by (S)CR 2249. Nevertheless, the efficacy of the glycine effect was enhanced in a concentration-dependent manner (3-10-30 microm) by (S)CR 2249. The interaction of (S)CR 2249 with NMDA receptors was also studied with binding experiments, in which we examined the effect of (S)CR 2249 on the modulation by glutamate, glycine and spermine of [3H]dizocilpine (MK-801) binding. (S)CR 2249, increased [3H]MK-801 binding in a concentration-dependent manner and we found positive cooperative interactions between glycine and (S)CR 2249, indicating that (S)CR 2249 probably acts at a separate allosteric site to increase NMDA receptor functionality.

Benzodiazepine-withdrawal-induced gastric emptying disturbances in rats: evidence for serotonin receptor involvement

This study was performed in rats to determine if serotonin and its receptors are involved in the increase of gastric emptying (GE) induced by benzodiazepine (BZ) withdrawal. GE was measured with a test meal (2 ml) containing 1 microCi/ml of 51Cr sodium chromate administered in rats, either previously receiving injections with diazepam (15 mg/kg/day i.p.) or with DMSO (0.9 ml/day i.p.) during 7 days. On the 8th day, animals received the different serotonin (5-HT) agonists or antagonists, and flumazenil (BZ antagonist; 15 mg/kg i.p.) 30 and 15 min, respectively, before the test meal. Methiotepin (5-HT1 antagonist) either i.p. (0.1-1 mg/kg) or intracerebroventricularly (10 micrograms/kg) had no effect on the increase of GE induced by precipitated-withdrawal. 8-OH-DPAT (5-HT1A agonist) administered i.c.v. (1-10 micrograms/kg) dose dependently reduced GE increase. Administered i.p. (0.1 mg/kg), it blocked GE increase in control and diazepam-withdrawn rats. Ritanserin (5-HT2 antagonist) antagonized GE increase only when administered i.p. (0.1 mg/kg). Granisetron (5-HT3 antagonist) was active both i.p. (0.01-0.1 mg/kg) and intracerebroventricularly (1-10 micrograms/kg). Administered intracerebroventricularly (1 microgram/kg) in diazepam-treated rats, 5-HTP mimicked the effect of flumazenil. It is concluded that diazepam-withdrawal increases GE by stimulating central release of 5-HT and/or central activation of 5-HT neurons. At least central 5-HT3 receptors, and in less extend, peripheral 5-HT2 receptors are involved in this mechanism.

Gastrointestinal effects of diazepam-withdrawal are linked to activation of central cholecystokinin-ergic pathways in rats

The influence of flumazenil-precipitated diazepam withdrawal on intestinal myoelectric activity and colonic transit was evaluated, in diazepam-dependent rats. Administered intraperitoneally, flumazenil (15 mg kg-1) induced a strong stimulation of the duodenal spiking activity lasting 197 +/- 20 min, and accelerated colonic transit corresponding to a significantly (P < 0.05) increased value of the geometric centre (3.52 +/- 0.23 vs 2.44 +/- 0.1 for the control). Both devazepide and L365260 administered intracerebroventricularly at a dose of 10 micrograms kg-1 abolished the flumazenil-induced withdrawal effect on the duodenum, whereas at a lower dose (1 microgram kg-1) only L365260 was able to antagonize this effect. In the same way, devazepide, loxiglumide and L365260 suppressed the effect of precipitated withdrawal on colonic transit when administered intracerebroventricularly at a dose of 10 micrograms kg-1, whereas similar blockade was obtained at a dose of 5 micrograms kg-1 with L365260, and 10 ng kg-1 with PD135-158. It is concluded that in rats precipitated diazepam-withdrawal altered intestinal motility and colonic transit and that these effects are mediated by central release of cholecystokinin (CCK) or activation of CCK-ergic neurons.

Different location of benzodiazepine sites involved in gut and behavioral effects of benzodiazepine withdrawal in rats

This work was performed to determine if the alterations in gastric emptying induced by precipitated withdrawal are linked to peripherally or centrally located benzodiazepine sites, in rats treated chronically with diazepam (15 mg/kg/day IP) for 7 days. In sham-capsaicin-treated rats, precipitated withdrawal by flumazenil (15 mg/kg IP) induced an increase of gastric emptying, whereas it had no effect in systemic capsaicin-treated rats. Both groups of animals developed withdrawal syndrome expressed as motor, autonomic, and behavioral signs. On diazepam-dependent rats, central administration of flumazenil (0.15 mg/kg ICV) induced withdrawal syndrome but had no effect on gastric emptying. These preliminary results suggest that benzodiazepine receptors located in the central nervous system are involved in behavioral withdrawal syndrome, whereas benzodiazepine receptors located at the peripheral level are responsible for digestive withdrawal syndrome involving capsaicin-sensitive neurons.

Benzodiazepine-induced intestinal motor disturbances in rats: mediation by omega 2 (BZ2) sites on capsaicin-sensitive afferent neurones

1. The central and peripheral effects of the omega (benzodiazepine) site ligands, clonazepam, alpidem, zolpidem, triazolam, flumazenil, ethyl beta carboline-3-carboxylate (beta-CCE) and N-methyl beta carboline-3-carboxylate (beta-CCM) on intestinal myoelectrical activity were evaluated in conscious rats, chronically fitted with Nichrome electrodes implanted on the duodenum and jejunum. The localization of the omega (benzodiazepine) receptors involved in these effects was evaluated by use of systemic and perivagal capsaicin treatments. 2. When administered intraperitoneally (i.p.) the omega site inverse agonists beta-CCE and beta-CCM, and the omega site antagonist flumazenil, did not affect the duodeno-jejunal motility. Alpidem and zolpidem, two selective omega 1 site agonists induced an inhibition of migrating myoelectric complexes (MMCs) only at a high dose (5 mg kg-1). In contrast, clonazepam (a mixed omega 1/omega 2 agonist) and triazolam (a preferential omega 2 site agonist) disrupted the MMC-pattern at doses as low as 0.05 mg kg-1, the effect of trizolam being of much longer duration than that of clonazepam. None of these drugs altered MMC-pattern when administered centrally (i.c.v.). 3. Administered i.p. or i.c.v. prior to triazolam, alpidem blocked the effect of triazolam on duodenojejunal spike activity. Administered i.p. prior to triazolam, flumazenil suppressed the triazolam-induced MMC-disruption. Previous systemic but not perivagal capsaicin treatment suppressed the effects of clonazepam on MMCs. 4. It is concluded that omega-site agonists but not, antagonist or inverse agonists, administered systemically induced intestinal motor disturbances which may be linked to activation of omega 2 (BZ2) sites located on nonvagal capsaicin-sensitive afferent neurones.

Clonazepam-induced intestinal motor disturbances are linked to central nervous system release of cholecystokinin in rats

The central and peripheral effects of clonazepam (central benzodiazepine receptor agonist) on intestinal myoelectrical activity and the origin of the effects were evaluated in conscious rats, chronically fitted with Nichrome electrodes implanted on the jejunum and with an intracerebroventricular (i.c.v.) cannula. Administered intraperitoneally (i.p.) in 12-h fasted rats, clonazepam (0.05 to 0.5 mg/kg) dose dependently disrupted jejunal cyclic migrating myoelectric complexes, characterizing the fasted state, which were replaced by a permanent irregular spiking activity, lasting 259 +/- 37 min for clonazepam at the dose of 0.5 mg/kg. This disruption of migrating myoelectric complexes occurred after a delay which increased with increasing clonazepam doses. In contrast, injected i.c.v. at doses from 1 microgram/kg to 1 mg/kg, clonazepam did not alter the migrating myoelectric complexes pattern of the small intestine. Injected i.p., flumazenil (central benzodiazepine receptor antagonist) (1 mg/kg) but not PK 11-195 (peripheral benzodiazepine receptor antagonist) (5 mg/kg) suppressed the effects of i.p. clonazepam (0.1 mg/kg). Administered i.c.v., 10 min prior to clonazepam (0.1 mg/kg i.p.), devazepide (CCKA receptor antagonist) at a dose as low as 10 ng/kg reduced the migrating myoelectric complex disruption induced by clonazepam. L365-260 (CCKB receptor antagonist) administered i.c.v reduced the migrating myoelectric complex disruption at 10-fold higher doses and loxiglumide (CCKA receptor antagonist) injected i.c.v, at 100-fold higher doses. When administered i.p. neither devazepide nor L365-260 affected the duration of migrating myoelectric complex disruption induced by clonazepam (0.1 mg/kg i.p.) or its delay of occurrence at doses lower than 0.1 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)